Sbp79-3b-ingles.p65

0021-7557/03/79-03/209
Jornal de Pediatria
Copyright 2003 by Sociedade Brasileira de Pediatria
ORIGINAL ARTICLE
Invasive pneumococcal strains isolated
from children and adolescents in Salvador
Cristiana M.C.N. Carvalho,1 Leda Solano de Freitas Souza,1 Otávio A. Moreno-Carvalho,2
Noraney N. Alves,3 Renilza M. Caldas,3 Maria G. Barberino,4 Jussara Duarte,4 Maria A. Brandão,4
Dilton R. Mendonça,5 Adriana Silva,5 Maria L. Guerra,6 Maria Cristina Brandileone,7 José L. Di Fabio8
Abstract
Objective: describe the antimicrobial resistance and serotype distribution of pneumococcal strains.
Methods: in a 57-month period, a laboratory-based surveillance of invasive pneumococcal strains
from patients aged < 20 years was conducted. Pneumococcus was identified by means of tests for solubilityin bile and optochin. Pneumococcal resistance to penicillin was screened by 1 µg oxacillin disc andminimal inhibitory concentration was determined for the strains not susceptible to penicillin. Discdiffusion and broth microdilution methods were used for surveillance of resistance to other antimicrobials.
Pneumococci were serotyped by means of the Neufeld-Quellung reactions.
Results: of 70 patients, 57.1% were males. The mean age was 1.92 yrs (mean 3.19 + 3.66 yrs, range
1 month to 19.5 yrs); 52.9% and 81.4% were < 2 yrs and < 5 yrs, respectively. The strains were isolatedfrom blood (91.4%), CSF (2.9%), pleural (2.9%), peritoneal (1.4%) and abscess (1.4%) fluids frompatients with pneumonia (77.1%), fever without localizing signs (10.0%), meningitis (4.3%), others(8.6%). Resistance was detected to penicillin (20.0%), trimethoprim-sulfamethoxazole (65.7%), tetracycline(21.4%), ofloxacin (6.3%), erythromycin (5.7%), clindamycin (2.9%). All tested strains were susceptibleto chloramphenicol and vancomycin. Among penicillin-resistant strains, high resistance was detected inone, the same that showed intermediate resistance to cefotaxime. The most frequent serotypes were: 14(22.9%), 5 and 6A (10.0% each), 6B and 19F (8.6% each), 9V, 18C and 23F (5.7% each). Resistance topenicillin was detected in serotypes 14 (71.4%), 6B and 19F (14.3% each).
Conclusions: of 70 strains, 67.2% were classified as serotypes included in the heptavalent conjugate
pneumococcal vaccine as well as were all penicillin-resistant strains.
J Pediatr (Rio J) 2003;79(3):209-14: Streptococcus pneumoniae, antimicrobial resistance, serotypes, invasive disease, children, adolescents.
Introduction
1. PhD, Universidade Federal da Bahia.
2. Specialist in Cerebrospinal Fluid, Cerebrospinal Fluid Laboratory - SINPEL, Streptococcus pneumoniae is an important etiologic agent, especially of pneumonia, meningitis, and sepsis, - the 3. Bacteriologist, Universidade Federal da Bahia.
4. Bacteriologist, Hospital Aliança, Bahia.
emphasis is on the pediatric age group in which it can cause 5. Pediatrician, Hospital Central Roberto Santos.
serious illness.1 The World Health Organization estimates 6. Biophysician, Instituto Adolfo Lutz, São Paulo.
7. Chief, Bacteriology Division, Instituto Adolfo Lutz.
that between 1 and 2 million deaths a year occur worldwide 8. PhD, Pan American Health Organization, Washington, DC.
among children younger than five years old as a result of This study was financially and technically supported by the Brazilian pneumococcal infections and the majority of these deaths Ministry of Health and the Pan American Health Organization.
Manuscript received Dec 10 2002, accepted for publication Mar 26 2003.
210 Jornal de Pediatria - Vol. 79, Nº3, 2003
Invasive pneumococcal strains isolated. – Nascimento-Carvalho CM et alii The rate of mortality per pneumococcal infection, immediately after the isolation of each invasive including pneumococcal pneumonia, underwent a massive pneumococcus strain. In this study strains from patients less decrease after the introduction of sulfa drugs and penicillin, than twenty years old were included.
between 1930 and 1940.3 The first sulfa-resistant strains ofpneumococcus had already been reported in 1943.4 In Bacteriological data
1965, for the first time, the occurrence of a strain of S.
pneumoniae which was resistant to penicillin was described.5 At the HUPES-CPPHO laboratory, until 1999, and at Since then, and particularly during the last ten years, in a the SINPEL, the biological fluid to be cultivated was large range of parts of the world, reports have become ever immediately innoculated (1.0 - 3.0 ml) in 30 ml of Brain more frequent of cases of infection caused by pneumococcus Heart Infusion (BHI) with SPS (0.025%) and incubated at with diminished susceptibility to, or even totally resistant to 35 ºC. All cultures underwent subcultures in agar-blood penicillin and/or other antimicrobials used in the treatment (lamb) at 5% and agar-chocolate, at 35 ºC, after 24 hrs, 48 of such infections;6-11 Brazil is not excluded.12-14 hrs and seven days’ incubation in the BHI. At the HUPES-CPPHO laboratory (from 2000 onwards), the HA and the In virtue of the data above, the use of a conjugated HCRS laboratories, 0.5-4.0 ml of the specimens collected pneumococcal vaccine which is immunogenic for children were immediately inoculated in 20 ml of supplemented BHI from two months of age onward has been considered as a and incubated in Organon Bact/Alert equipment at 35 oC, potential strategy for the control of pneumococcal for seven days. Whenever the equipment signaled a positive infections.15,16 Nevertheless, more than 90 different result, the medium was subjected to sub-culture in Columbia pneumococcus serotypes have already been identified and agar with 5% lamb’s blood and in agar-chocolate, incubated many of them are serotypes which cause disease.17 The at 35 oC with 5% CO , for 18-24 hours. S. pneumoniae was profile of which serotypes are most relevant varies from one distinguished from other alpha-hemolytic streptococcus by region to another18 and induced immunity is apparently means of tests for solubility in bile and optochin.
serotype-specific.15 Therefore, widespread conjugated Pneumococcus strains were sent to the Bahia Central pneumococcal vaccine use requires both adequate Laboratory (LACEN - BA- Laboratório Central da Bahia) knowledge of the distribution of the most prevalent serotypes and then to the Adolfo Lutz Institute, in São Paulo, where within each region and also the susceptibility of each bacteriological identification was confirmed and serotyping pneumococcus to antimicrobials in order to allow the choice and tests fro antimicrobial susceptibility were carried out.
of the correct therapeutic system to be made for the treatment Resistance of the pneumococcus to penicillin was initially identified through the use of an oxacillin 1 µg disc. The disc The objective of this investigation was to describe the diffusion method was used to identify resistance to other pattern of antimicrobial resistance and the distribution of antimicrobials including chloramphenicol, trimethoprim- serotypes of invasive pneumococcus strains as isolated sulfamethoxazole, erythromycin, clindamycin, ofloxacin, from a sample of children and adolescents in Salvador, vancomycin and tetracycline. When a strain was considered to have a diminished susceptibility to oxacillin (the bacterialgrowth inhibition zone around the oxacillin disc was smallerthan 20 mm) it was submitted for minimum inhibitory concentration (MIC) measurement for penicillin and forcefotaxime, by means of the plate microdilution method Population and design of study
(Mueller-Hinton broth supplemented with 2-5% lysed horse Between September 1997 and May 2002, active vigilance blood) (20). The following MIC values were used to was maintained of invasive pneumococcus strains. The determine susceptibility to penicillin: MIC < 0.06 µg/ml - Bacteriology Laboratories of the Hospital Complex which susceptible, 0.12 µg < MIC < 1.00 µg - intermediate includes the Professor Edgard Santos Teaching Hospital - resistance, MIC > 2.00 µg/ml - absolute resistance.20 The Professor Hosannah de Oliveira Pediatric Center (HUPES- pneumococci were serotyped by means of the Neufeld- CPPHO) and the Hospital Aliança (HA), during the entire Quellung reactions using antiserum produced by Statens period, of the Hospital Central Roberto Santos (HCRS) during 1999, and the Cerebrospinal Fluid Laboratory of theDivision of Pediatric Infectology and Cerebrospinal FluidAnalysis of Bahia (or State of Bahia)- Fundação José Study location
Silveira (SINPEL-FJS), during 2001 and 2002, in Salvador, The bacteriological laboratories at the HUPES- Bahia. Clinical and demographic data was collected on CPPHO, HA and HCRS perform examinations for patients those patients from whose normally sterile fluids cared for at their respective hospitals. O HUPES-CPPHO pneumococcus strains had been isolated. Data came from is a public university hospital, located in the central part information recorded on the culture requests or, when of Salvador and cares for patients of a predominantly low necessary, based on an interview of the assisting doctor or socio-economic status who come from Salvador and through consultation of the patient’s medical record, neighboring towns. The HCRS is public, located in a Invasive pneumococcal strains isolated. – Nascimento-Carvalho CM et alii Jornal de Pediatria - Vol. 79, Nº3, 2003 211
lower-middle and lower class residential district and susceptibility to ofloxacin, four (6.3%) proved themselves primarily cares for patients of low socio-economic status.
to be resistant, while among the 17 tested for susceptibility The HA is located in a high and medium socio-economic to cefotaxime , one (5.9%) was considered resistant. All class residential zone and cares for patients of these of the seventy strains were susceptible to chloramphenicol classes. The SINPEL-FJS performs cerebrospinal fluid as were the 44 strains tested for vancomycin susceptibility.
tests for patients cared for at seventeen hospitals Among the strains which were not susceptible to penicillin, throughout the city, from low, medium and high socio- absolute resistance was detected in one, the same which economic classes who come from Salvador and other presented intermediate resistance to cefotaxime. The towns in the state of Bahia. According to a study of median of the ages of the patients whose strains where community pneumonia in children and adolescents, penicillin resistant was 2.75 years (mean average 4.22 + conducted at the CPPHO and the HA, between 1997 and 4.74 years), with 35.7% being less than 2 years old and 1999, 7.4% of the children hospitalized with pneumonia 78.6% less than 5. Table 1 presents serotype distribution in Salvador are interned in one of these two hospitals,21 and the respective penicillin resistance frequencies. The where blood cultures are collected from 65.5% of this strain which had absolute resistance was classified as same group of patients and pneumococcus is isolated in Data analysis
The statistical analysis was descriptive and employed Distribution of serotypes of invasive pneumococcal the Statistical Package for Social Sciences (SPSS 9.0).
strains and penicillin resistance, Salvador, 1997-2002 Since the primary objective was to describe the pattern ofantimicrobial resistance of invasive pneumococcus, with an Frequency (%)
Resitance to
emphasis on penicillin, the sample size calculation was Serotypo
Cumulative
Penicillin (%)*
performed based on a resistance level of 20%, in agreementwith De Cunto Brandileone MC et al.13, a confidence interval of 95%, width of 20% giving a minimum sample size of 62 strains.23 Consent was obtained from the directorate of each hospital or service to which each of the respective satellite laboratories is attached. This study is an integrant of the Pan American Health Organization Epidemiological Surveillance Network for Streptococcus pneumoniae (SIREVA-VIGIA),24 in Bahia.
Seventy strains of pneumococcus were isolated: 55.7% at the HUPES-CPPHO, 41.5% at the HA, 1.4% at the SINPEL and 1.4% at the HCRS. The ages of the 70 patients varied from 1 month to 19.5 years, with a median of 1.92 years (mean average 3.19 + 3.66 years); 52.9% and 81.4% of the patients presented ages < 2 years and <5 years respectively; 57.1% of the patients were male.
Sorotypes in the serogroup 15 were not possible to type.
The strains were isolated from blood (91.4%),cerebrospinal fluid (2.9%), pleural fluid (2.9%),peritoneal fluid (1.4%) and fluid from an abscess (1.4%).
The diagnoses of the patients were pneumonia (77.1%),fever without localized symptoms (10.0%), meningitis(4.3%), cellulitis (2.9%), acute otitis media (2.9%), Discussion
sinusitis (1.4%) and peritonitis (1.4%). Of the 64 patients The elevated frequency pneumococcus strains isolated from whose blood pneumococcus were isolated, one from blood (91.4%) calls attention to itself when compared presented with meningitis. Of the 70 strains, penicillin with the frequency of strains isolated from other corporeal resistance was detected in 20.0%, resistance to fluids which are normally sterile (8.6%). This finding sulfamethoxazole-trimethoprim in 65.7%, to tetracycline indicates the practice of blood culture collection for patients in 21.4%, to erythromycin in 5.7%, to clindamycin in with suspected bacteremic disease at the hospitals which 2.9%; among the 64 strains which were tested for took part in this study. The frequency with which this 212 Jornal de Pediatria - Vol. 79, Nº3, 2003
Invasive pneumococcal strains isolated. – Nascimento-Carvalho CM et alii procedure was performed is not known. It is known that for patient, this procedure permits the study of the bacterial two of the hospitals (CPPHO and HA), between 1997 and 1999, blood cultures were collected from 65.5% of patients The rate of penicillin resistance reported here is similar with pneumonia aged less than 15 years.22 It is important to to the rates reported by other studies carried out in large point out that among the varied situations in which Brazilian cities.13,41 As this rate of absolute resistance is pneumococcus may be the cause of bacteremic disease, low, according to Friedland and McCracken, crystalline pneumonia, sepsis and occult bacteremia deserve to be penicillin remains the first choice of treatment for highlighted and are more frequent occurrences than pneumococcal infections with no central nervous system meningitis.1 Despite the elevated morbidity and lethality of involvement and which require hospital treatment, just as pneumococcal meningitis,25 many of which represent amoxycillin remains the first choice for treatment, at clinics subsequent stages of bacteremic disease, bacteremic diseases and outpatients units which do not require hospital without meningitis are more prevalent.26 Furthermore, there are reports that the distribution of serotypes which cause Approximately 85.0% of the pneumococcal infections bacteremia without meningitis may be different from the which occur globally within the pediatric age group are distribution of serotypes which cause bacteremia and caused by seven serogroups: 4, 6A/B, 9V, 14, 18C, 19F meningitis27,28 and that certain serotypes present higher and 23F,43 the same ones which are included in the frequencies of antimicrobial resistance than others.5,29,30 It heptavalent conjugated vaccine which has been licensed therefore follows that information about the antimicrobial for use.44 Of the strains presented here, 67.2% belonged susceptibility and of the distribution of the serotypes of to the serotypes which are included in the vaccine.16 Of strains isolated from blood is fundamentally important to the remaining serotypes, the most frequent in this sample the choice of epidemiological and clinical measures such as was serotype 5 (10.0%). The importance of the frequency the use of antimicrobials and vaccines.31 The number of of serotype 5 has been demonstrated before in tests that were performed in order to obtain the strains investigations carried out in South America and published isolated here is not a known variable.
previously.9,10,11,13,41 However, these same publications Within the sample presented in this work, 87.1% of the observed an important frequency of serotype 1,13,41 a strains were isolated from the blood of patients with fact which was not observed it the current study nor in an pneumonia or fever without localized symptoms. The investigation conducted here in Bahia, by Ko et al., in predominance of invasive pneumococcal infections among which patients with meningitis were studied.14 Despite children less than five years old attracts attention. The the small sample size of this study, the consonance of the majority were less than two years old (median 1.92 years), distribution with the results reported by other investigates which is in agreement with results previously documented reinforced the urgency of making available a vaccine by other authors.32,33 It is once more pointed out that which includes serotype 5, for use with the population at preventative strategies for this type of infection within this large, and, as such offering a wider protection.41 All of age group are important. Included among such strategies, the strains which presented penicillin resistance in this and deserving to be highlighted, is the use of the conjugated study belong to the serotypes contained in the conjugated vaccine which is immunogenic from an age of two months heptavalent vaccine, which thus proves to capable of offering protection against potentially more serious It has been estimated that between 5% and 10% of infections. As the greatest advantage of this vaccine is children with fever present fever without localized the fact that it is immunogenic for patients who are two symptoms.34 While the great majority of these children are or more months old and the greatest frequency of suffering from some sort of acute, auto-limiting and benign pneumococcal infections occurs in individuals younger infectious disease,35 5% are suffering from occult than 2,15 the data obtained through this research suggest bacteremia,35-38 of which S. pneumoniae is the most frequent that the currently available vaccine can bring benefits, cause in such situations.39 Furthermore, a study conducted within the region studied, to individuals who present the by Baron and Fink demonstrated that children cared for at greatest risk of pneumococcal infections, such as asplenic private surgeries had the same chance of having occult patients,45 or of more serious pneumococcal diseases, bacteremia as indigenous children.36 Therefore the such as patients with the Acquired Immunodeficiency importance of collecting blood cultures is further highlighted for children with fever without localized symptoms and riskfactors for occult bacteremia such as: age less than 3 years,temperature at axilla > 39 oC, leukocytes > 15,000/mm3 or References
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